OProfile overhead

OProfile is low-overhead in most common cases; this is dependent on
the interrupt load OProfile has to deal with. The below results were
obtained with a pre-release version of OProfile 0.7 on a 2.6.0-test7
kernel. The hardware was an HP Netserver LPr with two 400Mhz Pentium
IIs. The overhead shown is the real-time overhead for compiling a Linux
kernel several times whilst OProfile is collecting data.

The x axis shows the mean average of profiling interrupts received per
second. The y axis shows the relative percentage overhead of the
real time to complete the task.

For comparison, the default settings of OProfile cause around 2,000
interrupts per CPU to be generated.